Coincidence detector of the focused rotary electron beam kind



Dec. 12, 1950 R R. SCHRAMM 2,533,401 A COINCIDENCE DETECTOR OF THE FOCUSED ROTARY ELECTRON BEAM KIND Filed Sept. 14, 1949 2 Sheets-Sheet 1 KA mum p A J' /MAM INVENTOR.

Dec. 12, 1950 R R. SCHRAMM 2,533,401

COINCIDENCE DETECTOR OF THE FOCUSED ROTARY ELECTRON BEAM KIND Filed Sept. 14, 1949 2 Sheets-Sheet 2 3 BY T 1 i=0 4:

Patented Dec. 12, 1950 COINCIDENE DETECTOR OF THE FOCUSED ROTARY ELECTRON BEAM KIND Raymond B. Schramm, Bloomfield, N. l, assignmto National Union Radio Corporation, Orange, N. 5., a corporation of Delaware Application September 14, 1949, Serial No. 115,588

Claims. 1

This invention relates to electron tubes, and more particularly it relates to apparatus employing tubes of the focussed rotating electron beam kind such as disclosed in U. S. Patents #2A33A03 and #2217374.

A principal object of the invention is to provide an improved electron tube of the focussed rotatin electron beam kind.

Another object is to provide a focussed rotary electron beam tube having at least two separate sets of electron beam control cages which are excited from two separate multi-phase sources to determine or control the relative phase relations of the waves from said sources.

Another object is to provide an improved phasecomparing or controlling apparatus employing a novel construction of focussed rotary beam tube.

Another object is to provide an improved coding arrangement employing a novel construction of focussed rotary beam tube.

Another object is to provide an improved multiplex signalling system employing a novel construction of focussed rotary beam tube.

A feature of the invention relates to an electron tube having a central electron-emitting cathode which is surrounded by a series of electrostatic beam-focussing and rotation controlled electrodes, and by a similar series of other electrostatic beam-controlling electrodes, both series being excited by respective plural phase alternating currents whereby the amount of space current passing to any one of a series of output anodes is a function of the relative phases of the said two excitations.

Another feature relates to a focussed electron rotary beam tube having separate series of surrounding electrodes which are energized by respective multi-p'nase voltages to enable the tube to be used as a multi-channel coincidence detector.

A further feature relates to the novel organization, arrangement and relative location and interconnection of parts which cooperate to provide an improved electron tube of the rotary focussed beam kind.

Other features and advantages not specifically enumerated, will be apparent after a consideration of the fOllOWiIlg detailed descriptions and the appended claims.

In the drawing,

Fig. l is an elevational view, partly schematic, of a tube according to the invention.

Fig. 2 is a cross-sectional view of Fig. 1, taken along the line 2-2 thereof.

Fig. 3 is a schematic circuit diagram showing one typical application of the tube of Figs. 1 and 2.

Figs. 4, 5 and 6 are respective wave diagrams explanatory of Fig. 3.

Referring to Figs. 1 and 2, the numeral represents any suitable evacuated enclosing bulb or envelope within which is supported an electrode assembly or mount 2 according to the invention. The tube i may be provided with any usual base 3 carryin the various contact prongs t which are connected to the respective electrodes of the mount 2. The mount or electrode assembly 2 comprises a central electron-emitting cathode 5 which is preferably of the indirectly heated type, comprising a cylindrical metal sleeve 5 having its external surface provided with a coating of electron-emissive material. Suitably located within the sleeve 6 is any well-known heater wire or element 1 for raising the said coating to its electron-emissive temperature. concentrically sur rounding the cathode 5 is a cylindrical metal cage consisting of a series of metal slats 8-l3. Each of these metal slats is equally spaced from the adjacent slats to provid a series of windows Ml9. Likewise, each slat is provided throughout its central length with a grid or electron permeable window 2ll25. For a detailed description of a typical construction for such a cage, reference may be had to the article published in the Proceedings of the I. R. E., volume 36, number 11, November, 1948, entitled Electrostatically Focussed-Radial Beam Tube, and also as disclosed in the prior Patent #2A33A03. The construction of this cylindrical cage is such that in efiect it provides a series of equally-spaced electron permeable windows. While the drawing shows twelve such windows formed from six metal slats, it will be understood that a greater or less number may be employed, as will be apparent from the ensuing description. In any event, each of the slats is provided with a separate lead-in as indicated by the numerals ZS-3i in the schematic showing of Fig. 3.

The slat electrodes 8l3 are arranged to be connected to a suitable source of six-phase alternating current supply represented schematically in Fig. 3 by the block 32. Each of the six-phase windings of the source 32 is connected to a respective one of the slats 8-43 so that the excitation of each slat is out of phase with the excitation of the adjacent slat. The cathode 5 is arranged to be connected to a suitable positive biassing potential so that in conjunction with the excitation voltages applied to the slat 8l3,

the electrons are formed into a single-ended beam which is substantially focussed at the surface of each of the slats, and it also rotates around the axis of the cathode and past each slat at a rate determined by the cyclic frequency of the sixphase source 32, as explained in detail in the prior article in the Proceedings of the I. R. E., and in the prior Patent #1433403.

concentrically surrounding the slats 8l3 is another series of similar slats 33-38, each slat having a central longitudinal grid or electron permeable window 33-45 5. The slats are spaced apart circumferentially to provide a series of windows i-5il in radial alignment with the respective windows ltili. Likewise the grids. or windows 39lt are in radial alignment with the corresponding windows or grids 2il-25. Mounted in radial alignment with each of the windows Bil-56 are respective control grids Ell-52, each of which may comprise a pair of side rod supports, for example 63, be, around which is wound the usual fine grid wire 65. Mounted in radial alignment with each grid is a respective anode 68-71. All the anodes may be connected through a common load resistor or impedance l8 and to a source of positive direct current plate supply voltage represented by battery it, whose negative terminal may be grounded. Each anode is likewise connected through an individual coupling condenser 89-4, to a respective output channel or utilization device 92l 63.

The slats Sit-33 of the second cage are connected through their respective lead-in conductors it4-itl to corresponding respective phases of a six-phase alternating current source till which may be similar to so irce 32.

The focussed electron beam ill rotates con tinuously in the direction of the arrow at a uniform rate determined by the frequency of source 32, and as explained in said I. R. E. publication and in said patents. Consequently, the beam will successively and recurrently pass through the windows 8l@ of the first cage. If the voltage conditions supplied by source ill! at the corresponding windows 39-5t of the second cage in the proper phase relation at the instant the beam passes through the corresponding window of the first cage, electrons will pass through the respective window of the second cage and thence through the respective control grid 52, etc. to the respective output anode 66, etc.

It is clear therefore, that electron or space current can flow from the cathode to the successive anodes only when the multi-phase excitation field-a applied to the first and second cages are in proper relative phase. Thus, if source 32 is a source of known fixed phase and frequency, and source H0 is a source of adjustable phase and/or adjustable frequency, the phase or fre quenoy or" source Hi! can be adjusted until a signal of predetermined uniform amplitude reaches each of the respective devices e2 ies,

Merely for explanatory purposes, the devices nism between the two sources 32 and ill the beam of the cathode-ray tube will scan a uniform pattern. Any lack of phase or synchronism will then be indicated in this uniform pattern on the creen or" the cathode-ray tube.

From the foregoing, it will be seen that when the two sources- 32 and iii) are in like phase or synchronism, pulses of equal amplitude will reach the devices 92lt3. It may be desirable to produce these pulses only when the beam is passing through the central portion of each of the aligned windows in the two cages. For this purpose the control grids 65'll can be connected to ground through a suitable adjustable negative direct current biassing source- 5E2. This enables the portion of each cycle over which coincidence i registered between the rotating electron beam ill and the portion of the window in the second cage through which it is passing, to be narrowed in angular extent, and permits a much higher degree of synchronization of the phases of the sources it and iii: to be obtained. The accuracy thusobtainable in the synchronization of the phases is then a mere matter of physical construction determined by the size of the windows in the two cages and the characteristic of the control grids.

Merely by way of example, let it be resumed that the electron beam 5 ii is rotating at a speed 21m] caused by a six-phase voltage applied to the six slats il-i3, where in is the frequency of the six-phase If the six-phase supply applied to the slats 32 38 of the second is in phase synchro-nism with the first supply, then the wave form of the anode current would be as indicated in Fi 4. Should the six-phase voltage from source E it be out of phase with the tic1tage from source 32, a smaller total anode current or no anode current at all will flow.

It will be understood, of course, that the invention is not limit-ed to the comparison of two sources of the same frequency. For example, if the source 5 it has a frequency twice that of source 32, and if at the beginning of an observation the two sources are in phase, the anode current would be as indicated in Fig. 5. Similarly, if the frequency of the source lid is half the frequency of source 32, and if the observations start at the instant the two sources are in phase, the. anode current would be as indicated in Fig. 6. In other words, should the frequency of rotation of the two electrostatic fields applied respectively to the first and second cages be related by an integral number, the current to each anode will follow a definite sequence. For example, should the two sources be equal in frequ ncy and phase (assuming six-phase sources), current will flow to anodes till l? in sequential order. Should however, the frequency of the field applied to the second cage be non-integral with relation to the frequency applied to the first cage, for example in the ratio of 19 to 7, the current would flow to the respective anodes in the following sequence (assuming of course six-phase supply is used and twelve windows in each cage) d6, '53, cs, 75, ll], ll, '52, (ll, it, 69, 56, ll. Thus, by controlling the relative frequencies of the two sources, it is possible to determine the order in which each anode receives electron or space current. Consequently, by applying separate signal potentials to the input signal devices 5 53-42 3, it is possible to transmit coded intelligence. For example, each of the sources lit-42d may represent a corresponding multiplex input channel, and the devices 92-l 03 would represent corresponding multiplex output terminals. The coding of the transmission to the various channels can then be controlled either by changing the relative phase of the two sources 32 and I I; by changing their relative frequencies; or by changing both their relative frequencies and their relative phases.

While in the foregoing, reference has been made to six-phase sources and to cages having twelve windows with twelve corresponding control grids and anodes, it will be understood that this is done merely for purposes of explanation and that a greater or less number of phases and corresponding windows, control grids and anodes, can be employed without departing from the spirit and scope of the invention. Thus while in the foregoing the tube has been disclosed a of the type wherein the beam is electrostatically focussed, it will be understood that the focussing and rotation of the beam can be eilected electromagnetically as disclosed for example in U. S. Patent #2,217,774 and as described in the Journal of Applied Physics, volume XV, No. 10, pages 704, 709, October 1944.

What is claimed is:

1. Electron discharge tube apparatus having means to develop a rotating electron beam and including a central electron-emitting cathode, a first cage electrode having a series of sections defining electron permeable windows concentrically surrounding said cathode, means to excite said sections by respective phases of a first multiphase potential source; a second cage electrode surrounding the first cage electrode and having a series of sections defining electron permeable windows in radial alignment with the first mentioned windows but displaced radially therefrom, mean to excite the sections of said second cage with the respective phases from a second multiphase potential source, a plurality of anodes respectively aligned with said windows, and means to adjust the phase of one of said sources to produce recurring pulses of current at said anodes whose time spacing is controlled by the phase relation between said sources.

2. Electron discharge tube apparatus according to claim 1, in which said anodes are radially aligned with said windows.

3. Electron discharge tube apparatus according to claim 1, in which a series of control grids are located one between each anode and the radially aligned windows of said cage electrodes.

4. Electron discharge tube apparatus according to claim 1, in which one of said sources is of known fixed phase and the other of said sources is of adjustable phase.

5. Apparatus for detecting phase relations between two multi-phase signals comprising an electron discharge tube of the focussed rotary electron beam type and having a first cage electrode with a plurality of sections defining electron permeable windows through which the iocussed beam is arranged to pass during its rotary motion; a second cage electrode surrounding the first cage electrode and having a series of sections defining electron permeable windows in alignment with the first-mentioned windows and radially displaced therefrom, a plurality of anodes each in alignment with said windows, and means to apply respectively to said cage electrodes the signals whose relative phases are to be determined, to produce recurring current pulses at said anodes whose time spacing is determined by the said relative phases.

6. Apparatus according to claim 5, in which an elongated electron emitting cathode is concentrically mounted Within said first cage.

7. Apparatus according to claim 5, in which said first cage consists of "11 sections defining 2n windows, and the source of multi-phase signals is c'onneicted to said sections to provide 2n excitation phases.

8. Apparatus according to claim 5, in which each of said cages comprises a series of sections which define 2n windows where n is the number of sections, and the multi-phase signal applied to one of said cages provides 2n phases.

9. Apparatus of the type described, comprising, means to develop two multi-phase signals whose phases are to be compared, a central electronemitting cathode, a series of separate electrode members surrounding the cathode of define elec tron permeable windows between said members, each of said members having an individual electron permeable window, means connecting the phases of one of said signals respectively to said sections, another cage electrode surrounding the first cage electrode and having electrode members defining electron permeable windows between adjacent members and with each member also having an individual electron permeable window in the body thereof, the windows in both said cages being in radial alignment with each other but radially spaced from each other, means to apply the phases of the other multi-phase signal to the electrode members of said second cage, a plurality of output anodes one for each of the electron permeable windows in the second cage, and means for adjusting the phase of one of said multi-phase signals with respect to the phase of the other multi-phase signal to produce recurring current pulses at said anodes whose time spacing is controlled by the relative phase between said signals.

10. In combination, an electron discharge tube of the type having an electron-emitting cathode, a first multi-Windowed cage surrounding the cathode for developing therewith a focussed electron beam, means to apply a first multi-phase potential to said first cage electrode, a second multi-windowed cage electrode surrounding the first electrode and with the windows thereof in radial alignment with those of the first electrode and radially spaced therefrom, means to apply a second multi-phase potential to said second electrode, a plurality of output anodes one for each of the sets of said radially-aligned windows, a control grid for each anode, a plurality of signalling channels each connected respectively to one of said control grids, and means to adjust the relative phase relations between first and second multi-phase potentials to produce recurring current pulses in said channels with the time spacing between pulses correlated with the phase difierence between said two potentials.

RAYMOND R. SCHRAMM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,217,774 Skellett Oct. 15, 1940 2,345,115 Hall Mar. 28, 1944 2,390,884 Jansky Dec. 11, 1945 2,433,403 Skellett Dec. 30, 1947 2,494,670 Rajichman Jan. 17, 1950 

